A common task encountered in many chemical operation is to mix a lower pressure gas stream into a higher pressure gas stream to obtain a product stream which is at a pressure equal to the pressure of the higher pressure gas stream. In a typical hydrogen plant for example, a small portion of the hydrogen product at low pressure must be recycled to the higher pressure natural gas feed to provide hydrogen for the desulfurization of the natural gas. Without first equalizing the pressure of the two streams by either compressing the hydrogen stream or expanding the natural gas steam, no mixing can occur. The hydrogen stream is typically mechanically compressed via compressor to the pressure of the natural gas stream before mixing.